Conjuring water out of thin air

Conjuring water out of thin air

The desert is not the obvious place to look if you’re searching for industrial quantities of water. But to a number of researchers and entrepreneurs active in the field of water conservation, the arid landscape has an abundance of the clear wet stuff. You just need to know how to extract it.

The idea is not (quite) as far-fetched as it sounds. Even in harsh climates, the air is full of water vapour. And even though atmospheric water condensers have traditionally been expensive to maintain and run, technology has matured to the point of being commercially viable.

The timing is fortunate. With almost a billion people worldwide lacking access to clean drinking water and polluted water causing 840,000 deaths a year, according to the World Health Organization, there has never been a greater need for this type of technology.

One of the leading innovators is Israel’s Water-Gen. “As (former) army officers, we understood first-hand the criticality of water supply under combat conditions and the logistical complexity of keeping soldiers well hydrated,” explains founder and co-CEO Arye Kohavi. “So we came up with the idea of water from air as a solution that enables water generation on site, where it’s most needed, without complicated infrastructure or expensive transportation, but most importantly, from a renewable and abundant source that never runs dry.”

Water for 6,000 people

Known as the Genius, Water-Gen has a unique design that makes it highly energy efficient, enabling the system to produce 3,000 litres per day at 2 US cents per litre, enough to quench the thirst of 1,500 people.

The company has installed its systems in India, the US and Mexico. Similarly, Florida-based Aqua Sciences makes an Emergency Water Station that can, with its daily output of 12,000 litres, deliver affordable potable water for communities of up to 6,000 people in a crisis.

Yet both Water-Gen and Aqua Sciences have some major disadvantages as long-term solutions: they need energy (usually electric generators or external power) and trained professional operators. Water-Gen’s next step is to run its Genius on solar power. “We see this as a true game changer,” says Kohavi.

Another solution is to use wind power to produce water from air. The US’s VICILabs has developed WaterSeer, which is essentially an artificial well. A vertical wind turbine spins fan blades to draw air into a chamber two metres below the ground. Cooled by the surrounding earth, the air’s water vapour condenses to provide up to 37 litres a day of pure water. An “orchard” of 80 WaterSeers could provide enough water for 1,500 people.

A drop in the ocean

In a few regions, collecting fog – rather than dehumidifying air – can be a less expensive route to producing water. “It takes energy to transform atmospheric water vapour to a liquid,” explains Canadian water consultant Roland V. Wahlgren. “Fog is water already in the liquid state (cloud droplets) and does not require energy to change phase.”

Fog collectors (known as air wells, dew harvesters or fog fences) have been used as passive water collectors since ancient times. Canada’s FogQuest has been installing fog-collecting polyethylene or polypropylene meshes for nearly two decades.

"There are many sites and even a number of cities where there may be no option but to use water-from-air technologies to solve scarcity problems."

As big as 40 square metres, these are suspended like sails between tall masts in mainly mountainous regions of developing countries such as Chile, Haiti, Ecuador, Dominican Republic and Peru. Costing USD1,000 to USD1,500, a large fog collector produces 200 litres a day. But it works only where rain and fog regularly occur.

American NGO Warka Water, meanwhile, collects not only rain and fog, but also dew through a design that produces as much as 100 litres a day. A recent winner of the World Design Impact Prize, the team creates 9.5 m tall biomimetic water-collecting towers – ones which imitate structures found in nature, such as termite hives and cactus spines. “Warka Water is not one product, but a design philosophy,” says founder Arturo Vittori. “We try to use local materials, local resources and local people, and we adapt it to the local culture.” This means, for example, that locally sourced bamboo is used for the frame structure, and after a training course, villagers can build a Warka tower using basic manual tools.

Funded through a Kickstarter campaign, Warka Water has built a tower in southern Ethiopia, and a new project with Oxfam is preparing the ground for an installation in Haiti. The plan is to start mass production in 2019; Warka Water towers will cost around USD1,000.

Promising as it is, the entire approach has its limits. “Water-from-air technologies are a niche solution, best used in a complementary and hybrid manner along with other technologies appropriate for a specific site,” Wahlgren explains. “Regions suitable for fog collection are limited and the viability of dew collection is site and season dependent. However, there are many sites and even a number of cities where there may be no option but to use water-from-air technologies to solve scarcity problems.”

Why can’t we just dig more wells?

First and foremost, not every hole in the ground contains water, and even if it does it is often not drinkable. If water is deep underground, treadle pumps and electrical equipment are need to bring it up, which are both expensive and difficult to maintain. Furthermore, if we dig too may wells we overexploit aquifers – the underground layer of water-bearing permeable rock. This is counterproductive because it lowers the water table, resulting in the drying up of wells and springs.